During the construction of a boat, often a mold is used to create a composite hull. Single, two and three part female molds, used to build a hull of one set size and shape, are well known in the boat building industry. The single or unit mold is most suitable for a small boat; a two part mold, often split down the longitudinal center, is suitable for a larger boat as it makes the composite layup and demolding process easier; and a three part mold, with two sides and a transom, allows for scaffolding to reach the work surface. Conventional single, two or three part hull molds can only be used to create a hull of one size and shape; this is because the size and shape of the hull plug is transferred to the mold upon its construction, and subsequently to the final hull, with fixed results.
A problem long experienced by composite boat builders is that it is costly and sometimes impossible to change a mold to produce hulls of substantially different dimensions. Further, once changes are made to a mold, the ability to revert back to the original size is not possible without costly additional expenditures. One solution to this problem is to build or purchase a new mold for each desired hull shape and size; however, the process of building or purchasing a new mold is time consuming and expensive, and represents a major investment for most shipyards.
Another common problem with current molds is that they are often quite large and heavy, to facilitate the construction of large boat hulls. This causes them to take up large amounts of room in storage, and causes transport and disposal to be slow and expensive.
The size of molds used to create large boat hulls is often inhibitory to the construction process. During the construction of large hull boats, conventional boat hull construction techniques cannot be undertaken at work bench level. This causes resin drainage due to the vertical surface nature of conventional boat hull molds, resulting in resin rich and resin lean areas that weaken the laminate.
U.S. Pat. No. 5,875,732 describes a method for boat hull construction using a mold. The discussed mold is an example of a commonly used single part female mold, and the process to create the mold involves placing material in the mold and curing it. If used to construct a large boat hull, this mold suffers the aforementioned cost, configurability and resin drainage issues. Other variants of this method have the same issues; WO2006094114A2 is a similar process which replaces composite layup with injection molding, U.S. Pat. No. 6,723,272 describes stretching a membrane over the curing material in the female mold, U.S. Pat. Nos. 5,433,165 and 4,120,632 have male and female surfaces which sandwich the curing material. All of these methods of creating boat hulls contain a standard single, double or triple part female mold, and as such the foregoing discussion applies to them.
U.S. Pat. No. 4,695,032 discloses a convertible mold, which may be used to create boat hulls of different shapes. The mold disclosed in this document comprises a frame including bars and beams carrying movable heads supporting a lattice of slats. In order to configure this mold, one must adjust the frame structure to move the slats such that they form the female mold of the desired hull shape. Not only is this design expensive and complex, it suffers many of the same disadvantages of the other molds known in the art: it takes up large amounts of space, and its vertical walls cause resin drainage.
Therefore, it would be advantageous to provide a boat hull mold which solves the aforementioned problems.